//! Memory management system calls
//! SPDX-License-Identifier: MPL-2.0

const std = @import("std");
const SyscallReturn = @import("../return.zig").SyscallReturn;
const SyscallError = @import("../error.zig").SyscallError;
const Context = @import("../context.zig").Context;
const VirtAddr = @import("../context.zig").VirtAddr;
const Fd = @import("../context.zig").Fd;

/// Memory protection flags
pub const ProtFlags = struct {
    pub const PROT_NONE = 0x0;
    pub const PROT_READ = 0x1;
    pub const PROT_WRITE = 0x2;
    pub const PROT_EXEC = 0x4;
};

/// Memory mapping flags
pub const MapFlags = struct {
    pub const MAP_SHARED = 0x01;
    pub const MAP_PRIVATE = 0x02;
    pub const MAP_FIXED = 0x10;
    pub const MAP_ANONYMOUS = 0x20;
    pub const MAP_GROWSDOWN = 0x0100;
    pub const MAP_DENYWRITE = 0x0800;
    pub const MAP_EXECUTABLE = 0x1000;
    pub const MAP_LOCKED = 0x2000;
    pub const MAP_NORESERVE = 0x4000;
    pub const MAP_POPULATE = 0x8000;
    pub const MAP_NONBLOCK = 0x10000;
    pub const MAP_STACK = 0x20000;
    pub const MAP_HUGETLB = 0x40000;
};

/// Memory advice flags
pub const MadviseFlags = struct {
    pub const MADV_NORMAL = 0;
    pub const MADV_RANDOM = 1;
    pub const MADV_SEQUENTIAL = 2;
    pub const MADV_WILLNEED = 3;
    pub const MADV_DONTNEED = 4;
    pub const MADV_FREE = 8;
    pub const MADV_REMOVE = 9;
    pub const MADV_DONTFORK = 10;
    pub const MADV_DOFORK = 11;
    pub const MADV_MERGEABLE = 12;
    pub const MADV_UNMERGEABLE = 13;
    pub const MADV_HUGEPAGE = 14;
    pub const MADV_NOHUGEPAGE = 15;
    pub const MADV_DONTDUMP = 16;
    pub const MADV_DODUMP = 17;
};

/// Map memory into the process address space
pub fn sys_mmap(
    addr: VirtAddr,
    length: usize,
    prot: i32,
    flags: i32,
    fd: Fd,
    offset: i64,
    ctx: *Context,
) SyscallReturn {
    _ = addr;
    _ = length;
    _ = prot;
    _ = flags;
    _ = fd;
    _ = offset;
    _ = ctx;
    
    // Basic validation
    if (length == 0) {
        return SyscallReturn.error_return(SyscallError.EINVAL);
    }
    
    // TODO: Implement mmap
    // This would involve:
    // 1. Validating parameters
    // 2. Finding suitable virtual address space
    // 3. Creating VMA (Virtual Memory Area)
    // 4. Setting up page table entries
    // 5. Handling file mapping if fd is valid
    
    return SyscallReturn.error_return(SyscallError.ENOSYS);
}

/// Change memory protection
pub fn sys_mprotect(addr: VirtAddr, length: usize, prot: i32, ctx: *Context) SyscallReturn {
    _ = addr;
    _ = length;
    _ = prot;
    _ = ctx;
    
    // Basic validation
    if (length == 0) {
        return SyscallReturn.error_return(SyscallError.EINVAL);
    }
    
    // TODO: Implement mprotect
    return SyscallReturn.error_return(SyscallError.ENOSYS);
}

/// Unmap memory from the process address space
pub fn sys_munmap(addr: VirtAddr, length: usize, ctx: *Context) SyscallReturn {
    _ = addr;
    _ = length;
    _ = ctx;
    
    // Basic validation
    if (length == 0) {
        return SyscallReturn.error_return(SyscallError.EINVAL);
    }
    
    // TODO: Implement munmap
    return SyscallReturn.error_return(SyscallError.ENOSYS);
}

/// Change the program break (heap size)
pub fn sys_brk(addr: VirtAddr, ctx: *Context) SyscallReturn {
    _ = addr;
    _ = ctx;
    
    // TODO: Implement brk
    // This would involve:
    // 1. Getting current program break
    // 2. Validating new break address
    // 3. Expanding or shrinking heap
    // 4. Updating VMA structures
    
    return SyscallReturn.error_return(SyscallError.ENOSYS);
}

/// Give advice about memory usage
pub fn sys_madvise(addr: VirtAddr, length: usize, advice: i32, ctx: *Context) SyscallReturn {
    _ = addr;
    _ = length;
    _ = advice;
    _ = ctx;
    
    // Basic validation
    if (length == 0) {
        return SyscallReturn.error_return(SyscallError.EINVAL);
    }
    
    // TODO: Implement madvise
    return SyscallReturn.error_return(SyscallError.ENOSYS);
}

/// Remap a virtual memory area
pub fn sys_mremap(
    old_addr: VirtAddr,
    old_size: usize,
    new_size: usize,
    flags: i32,
    new_addr: VirtAddr,
    ctx: *Context,
) SyscallReturn {
    _ = old_addr;
    _ = old_size;
    _ = new_size;
    _ = flags;
    _ = new_addr;
    _ = ctx;
    
    // Basic validation
    if (old_size == 0 or new_size == 0) {
        return SyscallReturn.error_return(SyscallError.EINVAL);
    }
    
    // TODO: Implement mremap
    return SyscallReturn.error_return(SyscallError.ENOSYS);
}

/// Synchronize memory with storage
pub fn sys_msync(addr: VirtAddr, length: usize, flags: i32, ctx: *Context) SyscallReturn {
    _ = addr;
    _ = length;
    _ = flags;
    _ = ctx;
    
    // Basic validation
    if (length == 0) {
        return SyscallReturn.error_return(SyscallError.EINVAL);
    }
    
    // TODO: Implement msync
    return SyscallReturn.error_return(SyscallError.ENOSYS);
}